Borates, structural principles

The phase relations, stoichiometry and structural chemistry of the metal borates have been extensively studied because of their geochemical implications and technological importance. Borates are known in which the structural unit is mononuclear (1 B atom), bi-, tri-, tetra- or penta-nuclear, or in which there are polydimensional networks including glasses. The main structural principles underlying the bonding in crystalline metal borates are as follows " ... 

In 1970, Heller suggested a classification of borates based on the number of boron atoms in the fundamental building block . In 1971, J. R. Clark added, in an article on crystal chemistry of borates , a further principle as the fifth rule, namely that "the boric acid group, B(OH)3, may exist in isolated form in the presence of more complex polyanions, or such insular groups may themselves polymerize and attach to side-chains of more complex polyanions , as first observed in the crystal structures of veatchite and paraveatchite. In 1977, Christ and Clark reviewed the various principles and classifications in their article on a crystal-chemical classification of borate structures with emphasis on hydrated borates . In addition to a sixth rule. 

B. Blaschkowski, H. ling and H.-J. Meyer (2002) Angewandte Chemie International Edition, vol. 41, p. 3322 - Nitrido-borates of the lanthanides S5mthesis, structure principles and properties of a new class of compounds . 

Several general principles have been formulated in connection with the structural chemistry of borates ... 

In this sechon, first-principles findings on the intrinsic structural, electronic and electrochemical properties of lithium metal borates are presented in a comparative study of three isotopic LiMBOg (M = Mn, Fe and Co) as a case study from Ref. 32. Furthermore, Li diffusion paths, Li diffusivity, and anti-site defects are discussed as the possible causes of the slow kinetics of lithium metal borates. 

See colour insert.) (a) Crystal structure of monoclinic LiMBOj (M = Mn, Fe and Co), (b) MO5 and (c) LiO chains are interconnected by trigonal planar BOj. BOj is highlighted with bold dashed line. (Reprinted with permission from D.-H. Seo et al. First-principles study on lithium metal borate cathodes for lithium rechargeable batteries, Phys. Rev. B S3,2011,205127. Copyright 2011, American Physical Society.)... 

---